In garages, machine shops, tool shops and the like where the cleaning of greasy, oily and grimy parts is performed, commonly a cleaning solvent is applied to the parts as by dipping or spraying to remove the grease, oil, grime and other similar deposits from the part. Then the part is sprayed or washed with water to remove the solvent and any remaining dirt residue. Although the used solvent and water and the residue might simply be flushed down an open drain, resulting in both loss of the solvent and contamination of the water system, environmental considerations require that the solvent, water and residue be collected in some type of container for proper disposal. Also it would be desirable to separate the solvent from the dirt residue and water for later reuse.
One such type of cleaning fluid recovery apparatus which provides for solvent recovery and automatic discharge of the wash water used in the parts cleaning operation is disclosed in U.S. Pat. No. 4,317,720. The apparatus includes a tank for receiving the wash water and cleaning solvent, the latter of which floats atop the water by reason of it having a specific gravity less than that of the water. Also provided is a screen mounted at the open top of the tank for supporting parts to be cleaned, and a removable shallow tray mounted beneath the screen which serves to collect and retain dirt and sludge removed from the parts being cleaned.
The apparatus disclosed in such patent also includes an inverted, generally U-shaped drain pipe extending upwardly from the bottom wall of the tank. The drain pipe has inlet and outlet ends and an intermediate curved portion. The inlet end is located within and closely adjacent the bottom wall of the tank whereas the outlet end is located beneath such bottom wall. With such an arrangement, water will flow out of the tank through the drain pipe upon the level of the water in the tube reaching the inside radius of the curved portion of the pipe while the cleaning solvent remains in a layer on top of the water exteriorly of the drain pipe. The apparatus also is equipped with a signal tube attached to the tank to indicate when the fluid level has reached a height at which the solvent may begin to overflow the tank, at which time the solvent is drained into a collection receptacle for reuse or refinement.
While the inverted, U-shaped drain pipe provides for automatic removal of water in the manner described, its employment may result in undesirable consequences upon improper use and/or servicing of the apparatus. If for example the drain pipe should become filled with water such as by closing or restricting the outlet end thereof, a siphoning action could occur. This accordingly would undesirably result in the draining of substantially all the water as well as any solvent contained in the tank. Also, the water and solvent spilling over the removable shallow tray may carry with it some sludge and greasy residue which then would collect in the bottom of the tank and/or pass through the drain pipe for undesirable discharge with the water. Over time, sludge and greasy residue also may build up inside the drain pipe and choke off the flow of water, which would adversely affect the water discharge operation and render the apparatus particularly vulnerable to the siphoning action. To prevent this from happening, frequent and time consuming servicing may be necessary, which would involve removal of the solvent and water in the tank to permit removal and/or cleaning of the drain pipe.